Polyolefins and other polymers are frequently modified in order to improve their rheological and other physical properties. Various agents and techniques have been used to carry out such modifications. One such technique is the “coupling” together of polymer chains.
One method for coupling polymers, such as polyolefins, is to use a coupling agent, i.e., a molecule that is capable of providing a nitrene and/or carbene reactive group for insertion into a carbon-hydrogen bond (C—H) in the polymers. One such a class of agents is the sulfonyl azides which are described in WO 99/10424. When heated to an appropriate temperature, these azides react to form nitrene groups that can then insert into one or more C—H bonds in the polymers.
However, the sulfonyl azides (and other modifying agents for that matter) can be shock sensitive, i.e., they can react in response to shock or other external influences. Accordingly, a modifying agent may require protection against shock during its manufacture, processing, shipping and/or use. One such method is phlegmatization, i.e., combining the agent with another compound that is inert or less sensitive to shock and thus diluting the effect of any shock on the modifying agent. In these combinations the modifying agent is typically attached to a substrate (also known as a carrier) through a coating or precipitation process. However, these processes often produce a product in which the modifying agent is poorly attached to the carrier and/or the modifying agent forms in large crystals on the carrier which are then susceptible to easy breakage or other forms of attrition from the substrate. In turn, this can result in free, i.e., unattached, modifying agent mixed with the carrier, and such a modifying agent is much more susceptible to reaction from shock than a modifying agent that is securely bound to the substrate.